/*
 * contrib/citext/citext.c
 */
#include "postgres.h"

#include "access/hash.h"
#include "catalog/pg_collation.h"
#include "utils/builtins.h"
#include "utils/formatting.h"
#include "utils/varlena.h"

#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif

/*
 *        ====================
 *        FORWARD DECLARATIONS
 *        ====================
 */

static int32 citextcmp(text *left, text *right, Oid collid);

/*
 *        =================
 *        UTILITY FUNCTIONS
 *        =================
 */

/*
 * citextcmp()
 * Internal comparison function for citext strings.
 * Returns int32 negative, zero, or positive.
 */
static int32
citextcmp(text *left, text *right, Oid collid)
{
    char       *lcstr,
               *rcstr;
    int32        result;

    /*
     * We must do our str_tolower calls with DEFAULT_COLLATION_OID, not the
     * input collation as you might expect.  This is so that the behavior of
     * citext's equality and hashing functions is not collation-dependent.  We
     * should change this once the core infrastructure is able to cope with
     * collation-dependent equality and hashing functions.
     */

    lcstr = str_tolower(VARDATA_ANY(left), VARSIZE_ANY_EXHDR(left), DEFAULT_COLLATION_OID);
    rcstr = str_tolower(VARDATA_ANY(right), VARSIZE_ANY_EXHDR(right), DEFAULT_COLLATION_OID);

    result = varstr_cmp(lcstr, strlen(lcstr),
                        rcstr, strlen(rcstr),
                        collid);

    pfree(lcstr);
    pfree(rcstr);

    return result;
}

/*
 *        ==================
 *        INDEXING FUNCTIONS
 *        ==================
 */

PG_FUNCTION_INFO_V1(citext_cmp);

Datum
citext_cmp(PG_FUNCTION_ARGS)
{
    text       *left = PG_GETARG_TEXT_PP(0);
    text       *right = PG_GETARG_TEXT_PP(1);
    int32        result;

    result = citextcmp(left, right, PG_GET_COLLATION());

    PG_FREE_IF_COPY(left, 0);
    PG_FREE_IF_COPY(right, 1);

    PG_RETURN_INT32(result);
}

PG_FUNCTION_INFO_V1(citext_hash);

Datum
citext_hash(PG_FUNCTION_ARGS)
{
    text       *txt = PG_GETARG_TEXT_PP(0);
    char       *str;
    Datum        result;

    str = str_tolower(VARDATA_ANY(txt), VARSIZE_ANY_EXHDR(txt), DEFAULT_COLLATION_OID);
    result = hash_any((unsigned char *) str, strlen(str));
    pfree(str);

    /* Avoid leaking memory for toasted inputs */
    PG_FREE_IF_COPY(txt, 0);

    PG_RETURN_DATUM(result);
}

/*
 *        ==================
 *        OPERATOR FUNCTIONS
 *        ==================
 */

PG_FUNCTION_INFO_V1(citext_eq);

Datum
citext_eq(PG_FUNCTION_ARGS)
{
    text       *left = PG_GETARG_TEXT_PP(0);
    text       *right = PG_GETARG_TEXT_PP(1);
    char       *lcstr,
               *rcstr;
    bool        result;

    /* We can't compare lengths in advance of downcasing ... */

    lcstr = str_tolower(VARDATA_ANY(left), VARSIZE_ANY_EXHDR(left), DEFAULT_COLLATION_OID);
    rcstr = str_tolower(VARDATA_ANY(right), VARSIZE_ANY_EXHDR(right), DEFAULT_COLLATION_OID);

    /*
     * Since we only care about equality or not-equality, we can avoid all the
     * expense of strcoll() here, and just do bitwise comparison.
     */
    result = (strcmp(lcstr, rcstr) == 0);

    pfree(lcstr);
    pfree(rcstr);
    PG_FREE_IF_COPY(left, 0);
    PG_FREE_IF_COPY(right, 1);

    PG_RETURN_BOOL(result);
}

PG_FUNCTION_INFO_V1(citext_ne);

Datum
citext_ne(PG_FUNCTION_ARGS)
{
    text       *left = PG_GETARG_TEXT_PP(0);
    text       *right = PG_GETARG_TEXT_PP(1);
    char       *lcstr,
               *rcstr;
    bool        result;

    /* We can't compare lengths in advance of downcasing ... */

    lcstr = str_tolower(VARDATA_ANY(left), VARSIZE_ANY_EXHDR(left), DEFAULT_COLLATION_OID);
    rcstr = str_tolower(VARDATA_ANY(right), VARSIZE_ANY_EXHDR(right), DEFAULT_COLLATION_OID);

    /*
     * Since we only care about equality or not-equality, we can avoid all the
     * expense of strcoll() here, and just do bitwise comparison.
     */
    result = (strcmp(lcstr, rcstr) != 0);

    pfree(lcstr);
    pfree(rcstr);
    PG_FREE_IF_COPY(left, 0);
    PG_FREE_IF_COPY(right, 1);

    PG_RETURN_BOOL(result);
}

PG_FUNCTION_INFO_V1(citext_lt);

Datum
citext_lt(PG_FUNCTION_ARGS)
{
    text       *left = PG_GETARG_TEXT_PP(0);
    text       *right = PG_GETARG_TEXT_PP(1);
    bool        result;

    result = citextcmp(left, right, PG_GET_COLLATION()) < 0;

    PG_FREE_IF_COPY(left, 0);
    PG_FREE_IF_COPY(right, 1);

    PG_RETURN_BOOL(result);
}

PG_FUNCTION_INFO_V1(citext_le);

Datum
citext_le(PG_FUNCTION_ARGS)
{
    text       *left = PG_GETARG_TEXT_PP(0);
    text       *right = PG_GETARG_TEXT_PP(1);
    bool        result;

    result = citextcmp(left, right, PG_GET_COLLATION()) <= 0;

    PG_FREE_IF_COPY(left, 0);
    PG_FREE_IF_COPY(right, 1);

    PG_RETURN_BOOL(result);
}

PG_FUNCTION_INFO_V1(citext_gt);

Datum
citext_gt(PG_FUNCTION_ARGS)
{
    text       *left = PG_GETARG_TEXT_PP(0);
    text       *right = PG_GETARG_TEXT_PP(1);
    bool        result;

    result = citextcmp(left, right, PG_GET_COLLATION()) > 0;

    PG_FREE_IF_COPY(left, 0);
    PG_FREE_IF_COPY(right, 1);

    PG_RETURN_BOOL(result);
}

PG_FUNCTION_INFO_V1(citext_ge);

Datum
citext_ge(PG_FUNCTION_ARGS)
{
    text       *left = PG_GETARG_TEXT_PP(0);
    text       *right = PG_GETARG_TEXT_PP(1);
    bool        result;

    result = citextcmp(left, right, PG_GET_COLLATION()) >= 0;

    PG_FREE_IF_COPY(left, 0);
    PG_FREE_IF_COPY(right, 1);

    PG_RETURN_BOOL(result);
}

/*
 *        ===================
 *        AGGREGATE FUNCTIONS
 *        ===================
 */

PG_FUNCTION_INFO_V1(citext_smaller);

Datum
citext_smaller(PG_FUNCTION_ARGS)
{
    text       *left = PG_GETARG_TEXT_PP(0);
    text       *right = PG_GETARG_TEXT_PP(1);
    text       *result;

    result = citextcmp(left, right, PG_GET_COLLATION()) < 0 ? left : right;
    PG_RETURN_TEXT_P(result);
}

PG_FUNCTION_INFO_V1(citext_larger);

Datum
citext_larger(PG_FUNCTION_ARGS)
{
    text       *left = PG_GETARG_TEXT_PP(0);
    text       *right = PG_GETARG_TEXT_PP(1);
    text       *result;

    result = citextcmp(left, right, PG_GET_COLLATION()) > 0 ? left : right;
    PG_RETURN_TEXT_P(result);
}
